The present invention relates generally to a venting apparatus and more particularly to flame arresting venting apparatus.
The Code of Federal Regulations, Title 30, Part 18, states requirements for explosion-proof enclosures for electrically operated machines and accessories intended for use in gassy mines or tunnels. Specifically, such electrical enclosures must be so constructed as to withstand internal explosions of methane-air mixtures (1) without damage to or excessive distortion of walls or covers, and (2) without ignition of surrounding methane-air mixtures or discharge of flame from inside to outside the enclosures. As a result of these requirements, prior art electrical enclosures have usually been very heavy and constructed with close tolerance fits at potential flame paths. Enclosures of the foregoing type have been difficult to handle and repair, particularly in the larger sizes, because of their weight. The close tolerance fits are expensive to manufacture and difficult to maintain. The ability of the enclosures to withstand internal explosive pressure and contain any flame is sometimes questionable, especially after the enclosures are subject to wear.